Re: [RFC] [PATCH] audit: log module name on init_module

[Paul Moore <paul@paul-moore.com>]

On Thu, Jan 26, 2017 at 4:21 PM, Richard Guy Briggs <rgb@redhat.com> wrote:
> This adds a new auxiliary record MODULE_INIT to the SYSCALL event.
>
> We get finit_module for free since it made most sense to hook this in to
> load_module().
>
> https://github.com/linux-audit/audit-kernel/issues/7
> https://github.com/linux-audit/audit-kernel/wiki/RFE-Module-load-record-format

Consistency nit: capitalize the first letter in the wiki page words
(see the existing RFE pages)

> Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
> ---
>  include/linux/audit.h      |   12 ++++++++++++
>  include/uapi/linux/audit.h |    1 +
>  kernel/audit.h             |    3 +++
>  kernel/auditsc.c           |   20 ++++++++++++++++++++
>  kernel/module.c            |    5 ++++-
>  5 files changed, 40 insertions(+), 1 deletions(-)
>
> diff --git a/include/linux/audit.h b/include/linux/audit.h
> index 2be99b2..7bb23d5 100644
> --- a/include/linux/audit.h
> +++ b/include/linux/audit.h
> @@ -360,6 +360,7 @@ extern int __audit_log_bprm_fcaps(struct linux_binprm *bprm,
>                                   const struct cred *old);
>  extern void __audit_log_capset(const struct cred *new, const struct cred *old);
>  extern void __audit_mmap_fd(int fd, int flags);
> +extern void __audit_module_init(char *name);
>
>  static inline void audit_ipc_obj(struct kern_ipc_perm *ipcp)
>  {
> @@ -450,6 +451,12 @@ static inline void audit_mmap_fd(int fd, int flags)
>                 __audit_mmap_fd(fd, flags);
>  }
>
> +static inline void audit_module_init(char *name)
> +{
> +       if (!audit_dummy_context())
> +               __audit_module_init(name);
> +}

More on this below, but I was expecting the function above to named
audit_log_kern_module(), or something similar.

>  extern int audit_n_rules;
>  extern int audit_signals;
>  #else /* CONFIG_AUDITSYSCALL */
> @@ -561,6 +568,11 @@ static inline void audit_log_capset(const struct cred *new,
>  { }
>  static inline void audit_mmap_fd(int fd, int flags)
>  { }
> +
> +static inline void audit_module_init(char *name)
> +{
> +}
> +
>  static inline void audit_ptrace(struct task_struct *t)
>  { }
>  #define audit_n_rules 0
> diff --git a/include/uapi/linux/audit.h b/include/uapi/linux/audit.h
> index 3f24110..4a328b4 100644
> --- a/include/uapi/linux/audit.h
> +++ b/include/uapi/linux/audit.h
> @@ -111,6 +111,7 @@
>  #define AUDIT_PROCTITLE                1327    /* Proctitle emit event */
>  #define AUDIT_FEATURE_CHANGE   1328    /* audit log listing feature changes */
>  #define AUDIT_REPLACE          1329    /* Replace auditd if this packet unanswerd */
> +#define AUDIT_MODULE_INIT      1330    /* Module init event */
>
>  #define AUDIT_AVC              1400    /* SE Linux avc denial or grant */
>  #define AUDIT_SELINUX_ERR      1401    /* Internal SE Linux Errors */
> diff --git a/kernel/audit.h b/kernel/audit.h
> index 431444c..144b7eb 100644
> --- a/kernel/audit.h
> +++ b/kernel/audit.h
> @@ -199,6 +199,9 @@ struct audit_context {
>                 struct {
>                         int                     argc;
>                 } execve;
> +               struct {
> +                       char                    *name;
> +               } module;
>         };
>         int fds[2];
>         struct audit_proctitle proctitle;
> diff --git a/kernel/auditsc.c b/kernel/auditsc.c
> index bb5f504..3e12678 100644
> --- a/kernel/auditsc.c
> +++ b/kernel/auditsc.c
> @@ -1172,6 +1172,14 @@ out:
>         kfree(buf_head);
>  }
>
> +static void audit_log_kern_module(struct audit_context *context,
> +                                 struct audit_buffer **ab)
> +{
> +       audit_log_format(*ab, " name=");
> +       audit_log_untrustedstring(*ab, context->module.name);
> +       kfree(context->module.name);
> +}
> +
>  static void show_special(struct audit_context *context, int *call_panic)
>  {
>         struct audit_buffer *ab;
> @@ -1268,6 +1276,9 @@ static void show_special(struct audit_context *context, int *call_panic)
>         case AUDIT_EXECVE: {
>                 audit_log_execve_info(context, &ab);
>                 break; }
> +       case AUDIT_MODULE_INIT:
> +               audit_log_kern_module(context, &ab);
> +               break;

With the exception of AUDIT_EXECVE everything else in show_special()
is simply open coded inside the show_special() function; considering
that audit_log_kern_module() is trivial it seems like a separate
function isn't really needed here.

>         }
>         audit_log_end(ab);
>  }
> @@ -2368,6 +2379,15 @@ void __audit_mmap_fd(int fd, int flags)
>         context->type = AUDIT_MMAP;
>  }
>
> +void __audit_module_init(char *name)
> +{
> +       struct audit_context *context = current->audit_context;
> +
> +       context->module.name = kmalloc(strlen(name) + 1, GFP_KERNEL);
> +       strcpy(context->module.name, name);
> +       context->type = AUDIT_MODULE_INIT;
> +}
> +
>  static void audit_log_task(struct audit_buffer *ab)
>  {
>         kuid_t auid, uid;
> diff --git a/kernel/module.c b/kernel/module.c
> index 529efae..678407e 100644
> --- a/kernel/module.c
> +++ b/kernel/module.c
> @@ -61,6 +61,7 @@
>  #include <linux/pfn.h>
>  #include <linux/bsearch.h>
>  #include <linux/dynamic_debug.h>
> +#include <linux/audit.h>
>  #include <uapi/linux/module.h>
>  #include "module-internal.h"
>
> @@ -3593,6 +3594,8 @@ static int load_module(struct load_info *info, const char __user *uargs,
>                 goto free_copy;
>         }
>
> +       audit_module_init(mod->name);
> +
>         /* Reserve our place in the list. */
>         err = add_unformed_module(mod);
>         if (err)
> @@ -3681,7 +3684,7 @@ static int load_module(struct load_info *info, const char __user *uargs,
>                        mod->name, after_dashes);
>         }
>
> -       /* Link in to syfs. */
> +       /* Link in to sysfs. */
>         err = mod_sysfs_setup(mod, info, mod->kp, mod->num_kp);
>         if (err < 0)
>                 goto coming_cleanup;
> --
> 1.7.1
>
> --
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> Linux-audit@redhat.com
> https://www.redhat.com/mailman/listinfo/linux-audit

-- 
paul moore
www.paul-moore.com